This invention relates to vehicle anti-theft systems, and more particularly to such systems in which a fluid valve temporarily disables a function of the vehicle, preventing operation of the vehicle.
Various vehicle anti-theft arrangements have been proposed in the prior art, the most common of which include ignition locks, steering wheel locks, and alarm devices which provide audible and/or visible alarm indications. It is well known that systems of these types are easily compromised, and thus, sophisticated control systems have been proposed. Such systems generally include electronically activated control devices which disable the vehicle exhaust or fuel line systems. The more sophisticated systems employ input devices which respond only to specifically coded signals to activate and deactivate the system.
For example, in U.S. Pat. No. 4,300,057 granted to Pedro Batlle Crosas, there is disclosed an anti-theft apparatus for vehicles in which a valve in a hydraulic return circuit of the braking system is activated by an electronic circuit set off by specific voltages acting as an electronic code. Although the locking means is activated and deactivated by using the electrical power source of the vehicle, maintenance of the wheels in a locked or unlocked condition is not directly related to the power source because the control valve includes a dual effect coil having two windings which can be switched state only by specific voltages which make up an electronic code which controls the switching of the valve.
Another automobile anti-theft system is disclosed in U.S. Pat. No. 3,358,481 issued to Gregory J. Roszkowski. In this system, a valve in the fuel line is operated by power from a converter circuit which is energized by means of special key which incorporates part of the converter circuit. This converter circuit prevents a thief from defeating the purpose of the system by using a jumper cable to connect the available power source directly to protection device itself.